Detectives from the Los Angeles County Sheriff Department’s Special Victims Bureau have arrested a 30-year-old man for allegedly sexually molesting his 12-year-old stepdaughter, authorities said.

According to information from sheriff’s officials, the incident occurred about 10:15 a.m. Wednesday in the 28300 block of Willow Court in Saugus, an unincorporated area of the Santa Clarita Valley.

Investigators said in a news release that the child's mother returned home earlier than usual from work and went into her daughter's room to check on her. When she opened the door, she saw her husband on top of the girl, authorities said.